What are the key clinical features to consider when assessing a patient for subarachnoid haemorrhage in primary care?

When assessing a patient for subarachnoid haemorrhage (SAH) in primary care, key clinical features to consider include:

• Sudden onset of a severe headache, often described as a 'thunderclap' headache that peaks within 1 to 5 minutes, which is a red-flag symptom for SAH.
• Neck pain or stiffness and limited or painful neck flexion on examination.
• Photophobia (sensitivity to light).
• Nausea and vomiting.
• New neurological symptoms or signs such as reduced consciousness, seizures, or focal neurological deficits.
• Difficulty describing symptoms due to altered consciousness, language barriers, or learning disabilities should prompt obtaining a witness account of symptom onset without delaying referral.

Given the high risk of missed diagnosis and the need for urgent investigation, any patient presenting with unexplained acute severe headache and these features should be referred immediately to an emergency department for further assessment and diagnostic imaging.

Effective pain relief should be provided, and neurological assessment should consider any sedative effects of analgesia administered.

These features help differentiate SAH from other causes of headache and guide urgent referral decisions in primary care.

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